Impact Failure Behavior And Numerical Analysis Of Typical Fuselage Structural Element

The sub-cabin structure provides a large compressible area during the crash impact of transport aircraft.Cabin strut and cargo stanchion are the main vertical structures of the fuselage structure.Their energy absorption characteristics,deformation and failure behavior have an important influence on the energy absorption,deformation and failure modes of the entire fuselage structure.As an important supplementary method for experimental research,finite element simulation analysis is an indispensable research method in crashworthiness research.Accurate finite element simulation modeling technology is still a key problem to be solved in the crashworthiness research.This paper selects the cabin strut and cargo stanchion as the research objects,and studies the impact failure behavior from the two levels of material and element,combining experiments and simulations.First of all,for the 2024-T42 aluminum alloy material used in the typical structure element of the fuselage,dog bone specimens are designed and processed for quasi-static and dynamic tensile testing,and notched specimens are designed and processed for quasi-static tensile testing.The test results show that the strain rate effect on the flow stress of the material is not obvious,but it has certain effect on failure strain.Different stress states have a great effect on material failure strain.Secondly,based on the material tensile test data,a variety of material constitutive and failure models are established and compared.The calibrated Hartley-Srinivasan constitutive model and the GISSMO damage model agree best with the experimental data.The bolt joints are designed for dynamic tensile test and simulation.The result is that the lap plate is broken,and the test data law is consistent with that in the material test.The finite element simulation compares the accuracy of different material models.With reference to the actual fuselage structure element,C type stanchion specimens were designed for axial impact test and simulation,and C type strut specimens were designed for dynamic three-point bending test and simulation.With the same buckling failure mode,the peak impact loads of C type stanchion are the same and they are independent on impact speed.The dynamic three-point bending test is mainly used to calibrate simulation model under dynamic bending load.The impact simulation contrasts and analyzes the simulation results of different material models,and summarizes the key points of finite element simulation of dynamic impact failure of structures.Finally,a variable parameter analysis was performed using the experimentally verified finite element model.With same other conditions,the failure behavior under axial impact of C type element transfors from progressive failure to local buckling and then sudden local buckling as the thickness of the element increases;the failure behavior changes from progressive failure to local bucklingand then global buckling when the length of the element increases.The energy absorption of C-type element is mainly caused by plastic deformation,which makes C-type element produces as much plastic deformation as possible,which helps increase energy absorption.This paper discussed the impact failure behavior of typical fuselage structures element,and developed a finite element modeling method for structural impact failure.The research results can provide important support for crash simulation,design and verification of metal aircraft structures.